SciFi + Art = lower electric bill

What crazy TreeHugger equation is this? There already exists house paint that, when applied to interior walls in the normal manner, results in increased interior comfort and a significant reduction in heating and air conditioning bills. It does this using a technology similar to that deployed in "Low-E" windows. The paint is similar, but not identical to Low-E window functionality because, while Low-E paint reduces energy consumption year round, Low-E windows only are helpful during the heating season. The question comes to mind: "Why haven't I heard of this before"? It's fairly new and only one brand is currently distributed in the US. Plus it looks like every other water based house paint, and competes in a commodity market. Even Low-E windows took many decades to gain wide acceptance. How to speed it up?
Here's the creative part of the equation. Imagine muralists and public artists banding together to market their creative services to help curb climate change. Using the Low-E paint palette, they create sanctioned public art on interior walls of shopping centers; offices; airports; etc. When a repainting is scheduled for normal maintenance, building owners are enlisted to have professional interior painters do a Low-E paint base coat for the mural and also on adjacent walls, leaving scaffolding for the mural surface, and supplying the tinted paints for artists to use.

Local, state, and national juried contests are held and cash prizes awarded for artistic winners. The personal financial awards come, however, when the HVAC savings are documented, based on standard methods agreed to, in advance, by participating mall developers, HVAC industries and electrical utilities. Contributing artists get checks for the estimated commercial energy bill savings in year one, paid for by building owners. The PR outcome is obvious. Win for building owner. Win for utilities. Win for art. Win for the climate. It's a dream equation to which I'd like to awaken.

Greatly simplified technology overview:

The Invisible Heat Mirror: -- Low-E windows modestly cut heating bills because of an invisible, extremely thin coating of tin oxide on the window pane(s). The more windows you have, the more beneficial it is to go Low-E. With a double glazed Low-E window, for example, a type increasingly common in northern US, the tin layer might be on the outside-facing surface of the inner-most of the two panes. Without the Low-E coat, heat radiated from the home's interior moves easily through the window, toward the out of doors. With the tin coating in place on the pane, however, the coating reduces the rate at which heat energy is "emitted" outward, as electomagetic energy, from the inner pane. This reduced "emissivity" in the outbound direction means that the heat effectively turns around and heads back into your house. Hence, you don't feel a chill as much when sitting near the coated window and energy is saved.

Several materials, not just tin, can lower emissivity. Radiance brand paint uses powdered aluminum. Low-E additives are finely divided, non-toxic metals or inorganic salts

Remarkably, Low-E paint is beneficial in both the heating and the cooling season. During the "cooling season", heat is conducted into your home's walls from where the sun's rays are incident to exterior walls, eventually reaching the decorative painted surface you see every day. Because of the Low-E paint's lowered "emissivity", compared to ordinary decorative paints, less infrared heat is able to radiate inward, cutting the air conditioning load. Where does the heat go? Back out side, by outward conduction, followed by radiative loss to the atmosphere. Because there is less infrared heat radiating in, you feel more comfortable, especially when the AC fan is not blowing actively. This reinforces the energy saving desire to keep the thermostat set conservatively. So there is a secondary phychological feed back loop that's conservation-driving.

Several companies offer Low-E paint for interior attic roof surfaces. Note that this functionality is very different than that of aluminum, glass bead, or light pigmented roof coatings placed on the exterior surface of a roof or wall. These exterior coatings work by reflection only, not by controlling emissivity.

by: John Laumer

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